Planqorapm co



W. S. GRAFF BAKER.

RAILWAY TRAFFIC CONTROLLING APPARATUS.

APPLICATION FILED AUG. 18. 1911.

1,313,977, Patented A11". 26, 1919.

I? W T WITNESSES \HB COLUMBIA PLANOGRAPII c0.. WASHINGTON. D. c.

UNITED STATES PATENT OFFICE.

WILLIAM S. GRAFF BAKER, OF LONDON, ENGLAND, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OF PENN- SYLVANIA.

Specification of Letters Patent.

Patented Aug. 26, 1919.

Application filed August 18, 1917. Serial No. 187,021.

To all whom it may concern:

Be it known that I, VILLIAM SEBASTIAN GRAFF BAKER, a citizen of the United States of America, residing at London, in the county of Middlesex, England, have invented certain new and useful Improvements in Railway-Trailic-Controlling Apparatus, of which the following is a specification.

My invention relates to railway traffic controlling apparatus and particularly to block signaling systems.

I will describe one form of block signaling system embodying my invention and will then point out the novel features thereof in claims.

The accompanying drawing is a view showing diagrammatically one form of block signaling system embodying my invention.

Referring to the drawing in detail, my invention in this embodiment is here shown applied to a single section of railway track B over which traffic normally moves in the direction indicated by the arrow. This section B is only one of a plurality of such sections constituting a railway wherein the sections are defined and insulated from adjoining sections by suitable means, such, for example, as insulated joints 1010, etc.

T designates a transformer, the primary of which is connected to a generator (not shown) while the secondary is connected across the track rails of the section B adjacent the entrance end of such section by means of leads 11 and 12. Connected in with the lead 12 and in series with the secondary of the transformer T is signal designated R, which, as here shown, is an electric lamp. A second signal G, which is also in the form of an electric lamp, is connected across the track rails of the section B adjacent the exit end thereof by means of wires 13 nd 14:, and is preferably located at the entrance end of the section and in close roximity to the lamp R. The lamps R and E? are provided with red and green lenses or globes, respectively, so that when illuminated they will indicate stop and proceed respectively.

From the foregoing arrangement it will be seen'that a track circuit is formed wherein the lamps R and G are permanently connected in series with each other and with the secondary of transformer T, the track rails of section B serving to conduct current to and from the lamp G. The parts of this track circuit are so proportioned that when the section B is unoccu ied by a train or car, lamp R is extinguis ed and lamp G is! illuminated, as shown in the drawing, whereas when the section is occupied lamp G is extinguished and lamp R is illuminated. I obtain this operation of the signals R and G by making the resistance of the lamp G higher than the resistance of lamp R, although I do not limit myself to this particular manner of obtaining this operation. As the lamp R has a lower resistance than lamp G, it is obvious that with the transformer supplying current at a constant and predetermined voltage, and the resistances of the lamps properly proportioned with relation to such voltage, when the circuit is intact, as shown in the drawing, the current will be insuiiicient to illuminate the lamp R but su'flicient to illuminate the lamp G. However, should the lamp G be short-circuited by a low resistance shunt, such as the wheels and axles of a train or car, lamp G is extinguished, and since the resistance thereof is then removed from the circuit, the current in the remainder of the circuit is increased and is sufiicient to illuminate the lamp R. In order to compensate for variation in the resistance between the track rails of section B, for instance, in the case of a track exposed to climatic variations, a resistance X may be connected in shunt to the lamp R, as shown.

The operation of the signaling system is as follows: When the section B is unoccupied, as shown in the drawing, only lamp G is illuminated, which, by virtue of its green lens indicates proceed to trains or cars approaching from the left. However, when a train or car enters the section, the wheels and axles thereof constitute a low resistance shunt to lamp G whereby the latter is extinguished and the lamp R illuminated. With the lamp R illuminated, a stop indication is given by virtue of the red lens, thus cautioning a following train or car from entering the occupied section. The lamp R is maintained illuminated so long as the train or car occupies the section, but upon leaving the section the low resistance shunt is removed so that lamp G is again illuminated and lamp R extinguished. Thus the signaling system is restored to its normal condition for operation by succeeding trains or cars.

- claims 1 without departing from the spirit and scope of my invention.

Having thus described my invention, what Iclaimis: 1. A railway signaling system comprising a section of railway track, a source of current connected across the track rails of said section at one end thereof, a lamp interposed between said section and source of current,

and connected in-series with the latter, and

a second lamp connected across the track rails of said section at the other end thereof, said first-mentioned lamp having a, lower resistance than the secondlamp'.

2. A railway signaling system comprising a section of railway track, and a track circuit therefor including a source. of current, a pair of lamps and the track rails of said section, said track rails being interposed between and connecting said lamps in series with said source of current.

3. A railway signaling system COIIIPIlSiIlg a section of railway track, a track circuit therefor including a source of current and two slgnals having different resistances, sald rent connected across the rails of said sec-;

tion, a signal lamp. included in the connec tion between one terminal of said source and one ra1l, and second signal. lamp connectedacross the rails of said section.

5. railway signaling system comprising. a section of railway track, a trackcircuit therefor including a source of current and two electric lamps, the parts of said track circuit, being so proportioned that one of said lamps is extinguished and the otherilluminated whensaid, section occupied, and that the first lamp is illuminated and the second extinguished when the section is unoccupied. V

6. A rallway signaling system comprlslng a section of railway track, a sourceof ourrent connected across the rails of said section, a signal lamp, included in the connectlon between one term nal of saidsource and one rail, a, resistance connected across the terminals of said lamp, and a second signal lamp connected across the rails of said section.

In testimony whereofpl have signed my name to this specification in the presence of two subscribing witnesses. 7

WILLIAM S. GRAFF BAKER.

Witnesses A V i GEO. Foanm, E. J meson.

Gopies of this patent may be obtained for five cents each, by addressing the Qommissioner of Patents,

Washington, D. G. 

